It peaked at 4.05% in March. The last 2 months it went just below 4% as the Unknown category increased. For June the reverse happened, so 4.04% seems to be the real current share of Linux on Desktop as desktop clients were read properly/werent spoofed.
User agents were commonly used for the wrong reasons - fingerprinting, sites that block particular browsers rather than using proper feature detection, etc. so I’m glad to see them slowly going away.